Liquid product pressure treatment method and device

ABSTRACT

A method and device related to a liquid product pressure and (optionally) temperature treatment method reduces the level of microorganisms in the liquid product to a preselected level. Utilizing the method, liquid product is diffused in a chamber with the speed of pressure variation of liquid product in one embodiment of about 10 9  Pa/sec. The preferred speed of the diffused drops is about 10 m/sec. The liquid product can optionally be heated before or during diffusion, and is preferably heated as a diffused liquid product by mixing it with superheated steam.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/772,610 filed May 3, 2010, which is a continuation of and claimspriority to U.S. application Ser. No. 11/821,216 filed Jun. 22, 2007,which is a continuation-in-part of and claims priority to InternationalApplication No. PCT/IB2005/003879, filed Dec. 22, 2005, which claimspriority to Russian Federation Application Serial No.2004137687/13(040980), filed Dec. 23, 2004 by inventors Andrie A.Volkov, Nikolay V. Arofikin and Alexander Y. Kolesnov, the disclosuresof which are not inconsistent with the present disclosure areincorporated herein by reference.

FIELD OF THE INVENTION

The invention is intended for use in any product in which it isnecessary to reduce the numbers of microorganisms, and is related to aliquid product pressure and (optionally) temperature treatment methodthat kills microorganisms, such as bacteria. The method can be used forliquid products or substances in any industry, such as the food orpharmacological industries.

BACKGROUND

There is a known method of liquid product thermal treatment intended todestroy harmful microorganisms (also referred to herein asmicroorganisms) wherein microorganisms are killed by mixing liquidproduct with a heating medium (e.g., sterile water steam) therebyheating the liquid product, and maintaining it at a temperature thatensures pasteurization or sterilization.

One drawback of this known method is that the liquid product mixes withwater when steam condenses during the process of product cooling. Thisincreases product mass on average by about 30% and as a result waterremoval is necessary. The water removal is connected with additionalsteps and expenses. Another drawback of this known method is potentialdeterioration of product quality and taste after pasteurization due todestruction of vitamins and protein coagulation because of thetemperature to which the product is raised.

Another known method with similar technical characteristics is one inwhich liquid product is mixed with a heating medium of condensing steam,and the liquid product is heated at a rate of about 1400° C./sec or morefor pasteurization and about 7600° C./sec or more for sterilization to atemperature not exceeding the temperature at which qualitative changesin liquid product takes place (such qualitative changes and temperaturesbeing known to those skilled in the art). The product is diffused intodrops preferably not exceeding 0.3 mm in diameter (this process isdescribed in Russian Patent No. 2,052,967, the disclosure of which thatis not inconsistent with the disclosure herein, is incorporated byreference). This method promotes efficient thermal treatment of theliquid product, sufficiently kills microorganisms and does not adverselyimpact the qualitative aspects of the liquid product, because itincreases the rate at which the liquid product is heated and onlymaintains the product at a high temperature for a short duration. Theliquid product is heated only to a temperature lower than that whichdoes not effect qualitative changes in the liquid product. This methodis performed in a pasteurization device, which contains a liquid productdiffuser, a pasteurization chamber, a nozzle for steam, a steamgenerator, a cooling chamber, and a vacuum pump.

A drawback of this method is that it does not exclude mixing of productwith steam condensate, and this can adversely impact the organolepticand physicochemical (such as taste, odor, color and consistency)stability of such liquid products, which include as non-frozenconcentrate (“NFC”) juices, and it does not guarantee the necessarydestruction of microorganisms that are heat resistant.

SUMMARY OF THE INVENTION

The purpose of the invention is to create an efficient liquid productpressure and (optionally) temperature treatment method and device thatpromote organoleptic and physicochemical stability of liquid products.It has been discovered that exposing a liquid product to a sharppressure differential, which may or may not be associated with heatingthe liquid product, destroys microorganisms, including microorganismsthat are heat resistant.

The problem can be solved by diffusing liquid product into drops(preferably into drops not exceeding about 0.3 mm in diameter) andexposing the liquid product to a speed of pressure variation of about10⁹ Pa/sec or more. Alternatively, the liquid product is exposed to aspeed of pressure variation of at least about 10⁵ Pa/sec. In thepreferred embodiment the speed of the drops speed is about 10 m/sec ormore and the pressure variation occurs during diffusion of the liquidproduct. The liquid product is diffused utilizing a nozzle and ismaintained at one pressure on one side of the nozzle (the pressure beingmeasurable and controllable, preferably by using a pump) and is releasedwhen diffused into a chamber on the other side of the nozzle where ithas a second pressure. The pressure of the chamber may also be regulatedand if it is, it is preferably regulated by the use of a vacuum pump.The chamber is preferably maintained at a pressure at or lower thanambient pressure. In one embodiment, the chamber is maintained at apressure lower than ambient pressure. In the preferred embodiment, avacuum source is connected to the chamber and the pressure in thechamber is maintained at about 0.25 Pa.

Optionally, the liquid product can also be heated during the process. Ifso, the heating is preferably performed in the chamber as the liquidproduct is diffused and can be done utilizing superheated steam or anyother suitable heating method (other options include ultrasonicfrequency or infrared light). Other suitable heating methods includeheating the walls of the chamber into which the liquid product isdiffused. The liquid product can also be heated by heating the walls ofthe chamber into which the liquid product is diffused without directcontact with the walls of the chamber. If steam is used it is preferablyintroduced into the chamber through a separate nozzle and is deliveredin the same direction as the liquid product. Further, the rate ofheating the liquid product preferably does not exceed 1100° C./sec inthe preferred embodiment, but any rate of heating can be utilized thatsufficiently kills the required number of microorganisms and that doesnot heat the liquid product to a temperature at which its qualitativeattributes are adversely affected. The heating step can be performed ata pressure at or lower than ambient temperature. In one embodiment, theheating step is performed at a pressure lower than ambient pressure.

A device for carrying out a method according to the invention preferablyincludes a chamber with a diffuser (preferably a nozzle), an optionalheat source (preferably a steam generator, an opening for releasingsteam (if steam is used) into the chamber, a cooling chamber, anoptional vacuum pump connected to the chamber and a vacuum controlvalve, and an optional steam super heater.

The technical result of the invention is a highly efficient treatmentmethod. The result is reached by the effect of short time productpressure change, which may be coupled with short time heating. Theprocess yields a required level (determined based upon the applicablegovernmental standard) of microbiological stability for liquid productswithout significant changes in their organoleptic or physicochemicalfeatures.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The device is illustrated in the attached drawings wherein

FIG. 1 shows a schematic of the device and

FIG. 2 shows the pressure and temperature conditioning chamber section.

In its preferred embodiment, device 100 contains (FIG. 1) a tank 1including chamber 4 used to treat liquid product. Tank 1 is connected topump 2 by a pipe to diffuser 3 (which is most preferably a stainlesssteel nozzle having an opening diameter of 1 to 3 mm) Nozzle 3 is inpressure and temperature conditioning chamber 4 that includes upper andlower parts that are connected to each other (and are preferablyhermetically sealed) along the flanges. At the upper part of the chamber4 there is nozzle 3, and the lower part of chamber 4 has vacuum controlblock 5, as best seen in FIG. 2. Device 100 further includes an optionalheat source, which as shown is steam generator 6 connected via pressurecontrol valve 7 to steam super heater 8, which in turn is connected tochamber 4 by a pipe. Device 100 also has cooling chamber 9 connected viapressure control valve 10 with condenser 11, tanks for condensation 12and finished products 13, 14, and a vacuum pump 15 for creating a vacuumin chamber 4 in this embodiment.

In the most preferred aspect of a method according to the invention aliquid product is sent under pressure to diffuser (shown here as anozzle) 3 where it is sprayed (or diffused) into chamber 4 from tank 1via a pipe connected with nozzle 3. The diffusion is preferablyperformed at 20° C. temperature and the liquid product is preferablydiffused into drops having a diameter generally not exceeding about 0.3mm (although it is possible that some drops would exceed this diametereven in the preferred embodiment). The speed of pressure variation forthe product is sufficient to kill a preselected microorganisms ormicroorganisms to a predetermined level, and this level is oftenrequired by a governmental standard. Determining the amount of pressuredifferential and (optionally) temperature required to kill a selectedmicrobe in a selected liquid can be determined through trial and error.The pressure differential to which liquid is subjected can vary widely.For example, the pressure differential can vary between at least 10⁵Pa/sec and no less than 10⁹ Pa/sec. In the preferred embodiment, thepressure differential to which the liquid product is subject is no lessthan 10⁹ Pa/sec. In another embodiment, the speed of pressure change inthe liquid product is subject is at least 10⁵ Pa/sec.

Further, in this embodiment the pressure in the chamber is maintained atabout 0.25 Pa, but it could be higher or lower since pressuredifferential per time is what kills the microorganisms. The pressure inchamber 4 is controlled by vacuum control block 5. The speed of thedrops in chamber 4 is preferably about 10 msec or more, although thismay vary according to desired operating parameters.

If heated, the liquid product is most preferably heated using steam fromsteam generator 6, which is regulated by valve 7. In this embodiment,steam is sent to steam super heater 8, where it is heated until it turnsinto a dry super heated water steam. Adding a steam super heater to thedevice is necessary for creating dry super heated water steam at lowpressure before it enters chamber 4. The addition of vacuum controlblock 5 to chamber 4 is desired for steam regulation to maintain thepressure at the necessary level.

Steam from steam super heater 8 is then sent via a pipe connected tochamber 4 for direct mixing with the diffused liquid product. The steamis preferably injected into chamber 4 through a separate nozzle and isinjected into the stream of diffused liquid product in the samedirection as the diffused liquid product is moving. In this embodiment,the liquid product is heated at a speed not exceeding 1100° C./sec,although any suitable heating rate can be utilized. The product isheated to a temperature that does not lead to its qualitative changes,such temperatures being specific to each liquid product and being knownto those skilled in the art. There is a balance between the streamcondensation on drops of product and water evaporation from drops ofproduct under achieved under certain conditions and parameters in thepressure and temperature treatment chamber. Optionally, the liquidproduct, if heated, could be heated using any other suitable method,such as infrared light or ultrasonic frequency, or by heating the wallsof the chamber.

The treated product together with steam are sent to cooling chamber 9where steam is removed with the help of condenser 11 and vacuum pump 15and the product is cooled down to the required temperature which dependson valve opening 10. Removed steam in the form of condensate is sent totank 12, while cooled product is sent to tank 13 or 14.

The use of the invention provides for microbiological stability of thetreated liquid product while preserving qualitative properties of theliquid product at their original levels or close to them. This is animportant feature for the industrial production of liquid products suchas milk, juices (such as reconstituted juices or NFC juices), nectarsand other products.

Example 1

Fresh milk at 20° C. was sent under a pressure of 7 bar to chamber 4from tank 1 via a pipe connected to diffuser 3. Diffuser 3 was of a typethat diffused the milk into droplets having a diameter not exceedingabout 0.3 mm, and in this example was a stainless steel nozzle. Thespeed of pressure reduction for the milk being diffused was 2.5×10⁹Pa/sec. The pressure at the diffuser was 6×10⁵ Pa, the diameter of theoutlet in the diffuser nozzle is 2 mm and the pressure in chamber 4 washeld at 0.25 Pa, although other operating conditions may be utilized.The droplet speed of the diffused liquid product in chamber 4 was notless than 10 m/sec. Steam from steam generator 6 regulated by valve 7was sent to steam super heater 8. Dry super-heated steam from steamsuper heater 8 was sent to chamber 4 for direct interaction withdiffused fresh milk. The time during which the droplets of milkinteracted with the steam was about 50 milliseconds. As a result themilk was heated to 65° C. which did not make any qualitative changes init. The milk was heated from 20° C. to 65° C. at a heating rate of 900°C./sec. Treated milk and steam were then sent to cooling chamber 9where, with the help of condenser 11 and vacuum pump 15, steam wasremoved and milk was cooled down to the target temperature of 31° C.which was controlled by valve opening 10, which was used to regulatewater vaporation. Removed steam in the form of condensate was kept intank 12, while the cooled milk was sent to tank 13.

The results of microbiological analysis of milk samples before and afterpressure and temperature treatment proving the efficiency of the appliedmethod and device are presented in Table 1, below:

TABLE 1 Results of the Microbiological Analysis of Treated Fresh MilkCFU in 1 ml of milk Before pressure and Microorganisms groupstemperature treatment After Bacteria of the group of 6 0 intestinalbacillus General bacteria 2.13 × 10² 0 Mezophile aerobic facultative 1.7 × 10⁴ 3.2 × 10³ anaerobic microorganisms

Example 2

The method was performed as described in Example 1, however NFC orangejuice was used as the liquid product.

Table 2 illustrates the efficiency of the present method and device forNFC orange juice.

TABLE 2 Results of the Microbiological Analysis of NFC Orange Juice CFUin 1 ml of NFC orange juice Before pressure and Microorganisms groupstemperature treatment After Mezophile aerobic facultative 4.6 × 10 0anaerobic microorganisms Yeast  5 × 10 0 Mold 4 0

Example 3

The method was performed as described in Example 1, howeverphysiological solution with E. coli culture was used as a liquidproduct.

Table 3 illustrates the efficiency of the present method and device forphysiological solution with E. coli culture.

TABLE 3 Results of the Microbiological Analysis of PhysiologicalSolution with E. Coli Culture CFU in 1 ml of physiological solutionBefore pressure and Microorganisms groups temperature treatment After E.coli 3.9 × 10⁷ 0

Examples 1, 2, and 3 do not cover all applications for the invention andare illustrative only. For example the present method and device mayalso be used for pressure and optional temperature treatment of suchliquid products as wine, foods, pharmaceuticals, blood plasma andothers.

Having now described the invention, variations that do not depart fromthe scope of the invention will become available to those skilled in theart. The invention is thus not limited to the foregoing description butis set forth in the following claims and legal equivalents thereof.Unless explicitly stated otherwise, method steps according to theinvention can be preformed in any order suitable of yielding a desiredproduct.

What is claimed is:
 1. A liquid product treatment method wherein liquidproduct is diffused into droplets while the speed of pressure change inthe liquid product is approximately 10⁵ Pa/sec or more and the speed ofthe droplets is about 10 m/sec or more during the process of diffusion.2. The method of claim 1 wherein the speed of pressure change in theliquid product is approximately 10⁹ Pa/sec or more.
 3. The method ofclaim 1 wherein the drops generally do not exceed 0.3 mm in diameter. 4.The method of claim 1 wherein the speed of the droplets is about 10³m/sec or more during the process of diffusion.
 5. The method of claim 1wherein the liquid product is milk.
 6. The method of claim 1 wherein theliquid product is orange juice.
 7. The method of claim 1 that furtherincludes the step of heating the liquid product prior to it beingdiffused.
 8. The method of claim 1 wherein the liquid product isdirectly mixed with a heating medium.
 9. The method of claim 8 whereinthe heating medium is steam.
 10. The method of claim 1 wherein theliquid product is heated to a temperature not exceeding a temperatureeffecting qualitative changes in the liquid product.
 11. The method ofclaim 1 wherein the liquid product is heated at a pressure equal to orlower than ambient pressure.
 12. The method of claim 1 wherein theliquid product is diffused by passing through a nozzle and being sprayedinto a chamber.
 13. The method of claim 12 wherein the liquid product isheated as it is diffused.
 14. The method of claim 13 wherein the liquidproduct is heated by steam and the steam is delivered into the chamberin the same direction as the liquid product is being diffused.
 15. Themethod of claim 1 wherein the liquid product is preheated beforediffusion to a temperature not exceeding a temperature level effectingqualitative changes in the liquid product.
 16. The method of claim 1that further includes the step of heating the walls of a chamber intowhich the liquid product is diffused.
 17. The method of claim 1 whichadditionally includes treatment of the liquid product with chemicallyactive gases, or components, gases or substances that kill bacteria. 18.The method of claim 1 wherein the one or more chemically active gasescomprise one or more of the group consisting of oxygen, chlorine andfluorine.
 19. The method of claim 1 wherein the liquid product isdiffused into a chamber and the chamber is maintained at a pressure ofabout 0.25 Pa.
 20. A device for implementation of a liquid productpressure treatment method, the device comprising a chamber, a diffuserin communication with the chamber, the diffuser for creating droplets ofthe liquid product that enter the chamber at a speed of about 10 m/secor more, a vacuum control unit in communication with the chamber,wherein the vacuum control unit creates a pressure change in liquidproduct entering the chamber of 10⁵ Pa/sec or more, and a heatingelement in communication with the chamber that heats the liquid productas it is being diffused at a rate that does not exceed 1100° C./sec. 21.The device of claim 20 that further includes a steam generator, acooling chamber, a vacuum pump, and a steam super heater.
 22. The deviceof claim 21 wherein the chamber is comprised of stainless steel.
 23. Thedevice of claim 20 wherein the diffuser is a nozzle.
 24. The device ofclaim 23 wherein the nozzle is comprised of stainless steel.
 25. Thedevice of claim 23 wherein the nozzle has an opening diameter between 1mm and 3 mm.
 26. The device of claim 23 wherein the chamber is about 70cm in diameter and 120 cm in height.